The LPC1800 series is offered with and without internal Flash. The Flashless versions, shown here in darker green, include large internal SRAM, up to 200KB, and combined with the NXP SPI Flash interface and an inexpensive external quad flash can provide a low cost system solution. The parts with internal Flash offer dual-bank Flash in sizes between 512 KB and 1MB. There are four families with the LPC1800 series: the 181x family is the basic set of parts. All peripherals are included except USB, Ethernet, and LCD. The 182x family adds the high speed USB which has on onboard high speed PHY. The 183x family adds the second USB which has an onboard full-speed PHY and a ULPI interface to interface to an external high-speed PHY and the Ethernet MAC. Finally, the 185x family adds the NXP graphic LCD controller. The 1812 and the 1813, or the 1822 and 1823, may look like the same 512k flash part, but the difference is the dual bank of memory. LPC1812 has a single bank of 512k Flash while the LPC1813 has 512k Flash in two 256k banks. If the customer does not require the dual bank capability then the 1812 would be the best choice. If the dual bank is desired then the designer can go with the 1813, and the higher Flash parts intrinsically have the dual banks built in. The smaller the package the fewer pins that can be brought out, obviously, so for full capability choose the BGA256 package. The 4300 part list is nearly identical except instead of LPC1857 it would be LPC4357, etc.